1. Technical Field
The present invention pertains to a heat dissipating internally fan-less housing for electronic circuits and components.
2. Description of the Background Art
Current housings for electronic components are in excess of heat-sink fins provided with an internal fan for cooling of electronic components. A fan inside the housing imposes limitations to the dimension of the housing and how electronic components for instance on a printed circuit board (PCB) should be mounted to accomplish best possible heat dissipating features. Fans provide a disadvantage in having a mechanical cooling mechanism with moving parts thus having a much shorter life length than a heat sink passive cooling mechanism.
A limitation imposed to a housing for the intended purpose of being utilized for instance for routers and switches in a broadband network is set by a standard for mounting in a rack or cabinet. This standard stipulates a 19 inch (48.26 cm) wide housing, a height or vertical space of one rack unit (1U), 1.75 inches (4.45 cm) and a maximum depth of 30 cm. The standard thus sets out limitations making it hard to mount fans outside and on top of a housing.
Another limitation for such a housing is set out by the possibility to mount status indicators and console ports on a front panel of the housing. Present techniques admit a one row mounting of for instance indicator LEDs on the front panel. If a plurality of rows of LEDs or other interfaces are to be mounted this could be accomplished by providing them on a rear panel. Such a mounting is undesirable, because it is favorable to be able to actually see all status indicators on the front panel for maintenance, status reading purposes or other. Numerous by hand chassis mounted LEDs are expensive compared to for instance LCD displays, but such displays require more space for mounting on a front panel than is currently available.
In current technology a possible technique for achieving a front panel mounting with a plurality of rows of indicators comprises, for example, to put a main PCB board as far to the bottom of the housing as possible and to additionally connect smaller/daughter PCB cards above the main board and mounting those to the front panel and connecting the smaller boards to the main board via cabling. A cabled connection is vulnerable to come loose and imposes additional manufacturing costs. Another disadvantage for a cabled connection between two boards is directed to molding of parts, especially if the additional board is mounted on the front panel, for example, molding of circuit boards in a heat dissipating substance such as silicone compounds with different elasticity could impose stress on cable connections. Using a daughter PCB card for additional interfaces or LED indicators forces a main board to be mounted in the bottom of the housing. When using heat sinks for cooling this would not provide enough cooling on the bottom of the housing since there is little or no space left for heat sink fins.
One other obvious reason for not having status indicators on a rear panel is that a rack or cabinet is often placed close to a wall with the rear panels facing the wall, or if not placed in this manner the rack is covered by a housing of screw attached or riveted metal sheets on the rear of the rack. The housing thus aims to protect rack-mounted equipment from dust, humidity, dirt etc. Hence, present rack mounted equipment is maintained or changed by pulling it out from its rack position and replacing it with new or maintained equipment.
Also, to overcome manufacturing costs, it would be appreciated that one and the same tool can be used for pressing the top and bottom parts of a housing and still fulfill the 19 inches, 1U rack standard.
SUMMARY OF THE INVENTION The present invention aims to provide a solution to the above mentioned and other problems in relation to rack-mounted equipment. For this purpose the invention sets forth a heat dissipating internally fan-less housing for electronic circuits and components. The housing comprises an assembly of two container parts comprising heat-sink fins each part having a substantially diagonal shaped profile. These parts are assembled to form the greater part of the housing as being substantially box shaped by positioning the diagonal profiles to form the box shape. In the housing is mounted a circuit-board along the diagonal profile thus providing that the long-side ends of the circuit-board on each side of the board are covered by a greater mass of heat-sink fins for a better cooling of components compared to a horizontally mounted circuit board.
In one embodiment of the present invention the container parts that form the housing are spaced apart through spacing/distance pieces, and the pieces are designed to be able to penetrate through apertures made in the circuit board.
Another embodiment comprises that the apertures have at least fitting allowance to the spacing pieces. A further embodiment comprises that the housing is filled with a heat dissipating elastic substance. This embodiment provides that the circuit board is laying floating in the heat dissipating substance substantially free from touching the housing. The circuit board thus in addition to heat dissipation being protected against damage imposed to the housing.
A still further embodiment comprises that the mounting of the circuit board in addition to a better cooling enables the mounting of multiple indicators and/or at least one display on long-side panels attached to the housing.
Yet a further embodiment provides that the housing dimension is adapted within stipulated standard rack measures for a 19-inch, 1U rack.
A further embodiment provides that fastening means enable the mounting of the housing in a vertical position in a rack, thus taking advantage of the chimney effect for heat dissipation.
Yet another embodiment provides that one long side of the housing is made shorter then the stipulated standard of 48.26 cm to fit at least one fan, and thereafter equipped with a smaller housing at one short side in order to fill a 19-inch rack standard.